Optically active hydroxy compounds are valuable chiral building blocks which are difficult to prepare with classical chemical processes. Hence biotechnological processes are usually considered for the production of chiral compounds either using whole cells of microorganisms or by means of isolated enzymes. As for example shown by the publication of F. Aragozzini et al. (Appl. Microbiol. Biotechnol. (1986) 24, 175-177), processes using whole cells often result in low yields, only a small enantiomeric excess (i.e. low ee values) and long reaction periods so that enzymes which can be used in a purified and concentrated form are more advantageous. In the case of chiral hydroxy compounds such as alcohols, alcohol dehydrogenases which reduce the prochiral compound with the aid of a coenzyme (often NADH or NADPH, may be used. As a rule these reactions are highly enantioselective. The previously available alcohol dehydrogenases (ADH) all lead to S-alcohols; the substrate spectrum for some of these enzymes is relatively narrow (yeast ADH, horse liver ADH). An NADP-dependent alcohol dehydrogenase from Lactobacillus kefir is described in DE 40 14 573 C1 and U.S. Pat. No. 5,200,335. This enzyme produces R-alcohols; however this enzyme is relatively unstable; thus purification to form a homogeneous enzyme could only be accomplished with substantial losses (&gt;98%).